The invention relates to semiconductor elements, in particular with a single photon avalanche diode, and a method for manufacturing a semiconductor element with a single photon avalanche diode.
Single photon avalanche diodes, SPADs, are photo diodes being reverse biased above the breakdown voltage. Photons of incident electromagnetic radiation such as light may generate free carriers in a multiplication zone of the SPAD and thus trigger an avalanche current of the reverse biased p-n junction of the SPAD. In this way, the incident radiation may be detected.
When an avalanche current is triggered by carriers generated thermally or through tunneling, a dark count event occurs. Dark count events may occur randomly. The number of dark count events per area in a certain time period may be denoted dark count rate, DCR, and is an important performance parameter for SPADs. Since dark count events increase the internal noise, a low DCR is desired.
Another key parameter of SPADs is photon detection probability, PDP, being the probability of obtaining a successful detection when a photon hits the SPAD. To initiate a photon triggered avalanche current, the electric field in the multiplication zone must exceed a critical field for avalanche multiplication. A high PDP is desired to increase the sensitivity and accuracy of the SPAD.